The clinical data of 195 patients in intensive care unit (ICU) were retrospectively analyzed. The total nosocomial infection rate was 15.5% in this group of patients; respiratory tract was the predominant site of infection (71.0%); the most common infection microorganism was Gram-negative bacteria (65. 1% ) ,the top two pathogens were Escherichia (32. 6% ) and Staphylococcus ( 11.6% ). The risk factors of nosocomial infection in ICU were female sex, high age, invasive mechanical ventilation, long hospitalization in ICU, multiple organ dysfunction syndrome (MODS), etc.